The major objective of this proposal is to supply comparative information on the environments, experiences, and intellectual and social development of young children age 18-36 months reared at home or attemding Day Care centers. A major aim is to provide detailed descriptions of the environments and experiences encountered by children in these two settings. A second aim is to discover which aspects of environments and experiences seem to promote or inhibit intellectual and social development in each setting. The research is designed to study these questions through systematic observations and evaluations of individual children carried out over a period of 18 months and through extensive interviews of teachers and parents.